Iostat for outputting CPU and disk input and output, partitions, Network File System NFS-related statistics. iostat command is used to monitor system input device I / O, and to generate reports, statistical reports according to modify the system configuration, obtain better performance.
iostat [-c] [-d] [-N] [-n] [-h] [-k | -m] [-t] [-V] [-x] [-z] [device [... ] | ALL] [-p [device [, ...] | ALL]] [interval [count]]
iostat can generate three types of reports: CPU utilization reports, equipment utilization reports, network file system utilization reports.
iostat command format can be summarized as follows:
iostat [parameters] [time] [number]
Wherein the time in seconds.
Simple to use 1, iostat command
iostat command can display the CPU load and I / O system and partition status information.
Direct execution iostat command can display the following contents:
# Iostat -xm
(With xm parameter displays extended information and disk data per sector to have displayed per megabyte  sector equals 512 bytes)
Meaning the output of the project are as follows:
1) avg-cpu paragraph:
% User: the user level operation of the percentage of CPU usage.
% Nice: nice operation percentage use of the CPU.
% System: at the system level (kernel) to run the percentage of CPU usage.
% Iowait: When the CPU waits for the hardware I / O, the percentage of CPU usage.
% Steal: the management of the program by maintaining a second virtual processor, a virtual CPU waits for the percentage of time unconscious.
% Idle: the percentage of CPU idle time.
tps: device per second I / O requests, a plurality of logical requests can be combined into "one I / O request."
Blk_read / s: read per second block number
Blk_wrtn / s: block number written per second
The total number of block read: Blk_read
Blk_wrtn: The total number of block write
wrqm / s write request after the merger, per second sent to the writing device requests.
2. Parameter Description iostat command
-c Display only CPU statistics. And -d options are mutually exclusive.
-d display only disk statistics. And -c options are mutually exclusive.
-k displayed in KB per second of disk requests, the default unit block.
-m displays in MB per second of disk requests.
-N Displays the disk array information
-n Display NFS network file system reports. This option is only available for Linux kernel 2.6.17 or later.
-p device | ALL
And -x options are mutually exclusive, for displaying statistics block device and system partition, you can specify a device name after -p, such as:
# Iostat -p hda
Or show all devices:
# Iostat -p ALL
-t When the output data, the print data collection time.
-V Print version number and helpful information.
-x output expansion information.